Vibratory conveying systems of various designs are well known in the art. One form of vibratory conveying system is the excited frame conveyor. An example of such a vibratory conveyor is seen in U.S. Pat. No. 4,313,535 to Carmichael and which is incorporated by reference herein. Still further, an excited frame conveyor which has an operational frequency greater than the first natural structural frequency of the frame is disclosed in U.S. patent application Ser. No. 09/810,307. The teachings of this pending application are also incorporated by reference herein.
Excited frame conveyors of these, and other similar designs, have provided many advantages over traditional vibratory conveyors inasmuch as these conveying systems are able to convey product efficiently, while simultaneously not transmitting vibratory force into the supporting surface upon which the conveying system rests or is suspended therefrom. In view of these performance characteristics, these types of conveyors are useful in various commercial environments where traditional vibratory conveyors would not be useful inasmuch as they would transmit too much vibratory energy into the supporting surface thereby potentially causing damage to the supporting surface or to the machine itself or further cannot be fabricated into the desired lengths which are useful in a given commercial environment.
Various control schemes have been devised in order to control the operation of excited frame conveyors. An example of a method of operating such an excited frame conveyor is found in U.S. Pat. No. 6,308,822, the teachings of which are incorporated by reference herein. In this patent, sensors are placed at various locations on the conveying apparatus and are coupled to a control assembly which is configured to monitor movement of various assemblies relative to the frame and determine the operational state of the conveying apparatus.
While these control schemes have operated with some degree of success, other perceived shortcomings have been noted with the prior art practices and assemblies described above. For example, in U.S. Pat. No. 6,079,550 an electromagnetic drive is described and which has a mass that vibrates back and forth along a substantially straight path. This mass is further connected to the frame of an excited frame conveyor and is operated in a fashion to provide, what is reported to be, several advantages relative to prior art drive assemblies employed in excited frame conveyors which utilize counter-rotating weights. In this regard, one of the reported advantages identified in U.S. Pat. No. 6,079,550 is the substantial elimination of transient vibrational motion of the excited frame and conveying member during start-up and shut-down of the conveyor system. It is reported in this patent that during these periods of transition, significant vibrational forces are transferred into the floor or ceiling supports which may result, on occasion, in catastrophic failures such as when a conveyor system becomes dislodged from its supports.
While this arrangement would appear satisfactory, at least on first analysis, this same arrangement is somewhat costly to manufacture and further includes a translating mass weighing several hundred pounds which creates a vibratory force which is transmitted substantially along a straight line, and which is reported to never match the natural frequency of the frame.
A conveying apparatus which avoids the perceived shortcomings and detriments in the prior art apparatuses and practices utilized heretofore is the subject matter of the present patent.